Tuesday, March 3, 2009

Normally when we install Wifi routers, we tend to place it as near to the cable modem or adsl modem as possible. This is mainly due to the fact that there aren't much places to consider because there are limited phone jacks and cable points around the house.

But do bear in mind that between the ADSL or cable modem to the wireless router, you can afford to lay a 30-40m network UTP cable without losing any speed or efficiency of the network speed.

So now that we know locating the wireless router within the house is not limited by the location of the modem, lets begin to learn what tools to use.

Normally for the average M$ Windows user, we rely a lot on the signal bar as shown by the networking icon on the bottom right corner of the screen. Usually this is a 4 bar indicator. However, the 4 bar indicator may not be entirely correct, no thanks to the people at Redmond.

In any case, there is an alternative software out there that does very detailed scans and display accurately the actual signal measured in "decibels".

Decibels is the proper unit of measure of a RF aka radio frequency waveform.

To put things into perspective, decibels (dB) are usually in the negative values.In the ambient surroundings, we have what we call white noise. This white noise is merely weak RF signals from all over mixing together and producing a non-important result. This "white noise" will usually have a power of -100dB.

Wifi signals transmitted to an intended recipient are expected to have a received signal power level of -60 to -85dB. These range is considered to be stronger [ aka more positive ] that -100dB. Naturally, if we were to plot the values out on a graph, the -100dB signal will be placed lower in the chart.

But if the transmitted signal travels too far or encounters too many obstacles, the received signal level seen at the receiving radio may be as low as -99dB. That is when problems arises. When a legible signal transmitted to the receiver location loses its power to the point that it is as good as noise, then the receiving radio will have problems trying to differentiate the original signal from noise itself.

Imagine speaking in a normal tone in a canteen full of kids during their break. This is somewhat similar when a signal strength seen at the receiving radio is near to the white noise signal strength.

A tool is commonly used by amateurs and wireless professionals alike for deploying wifi locations in order to maximise coverage, performance and efficiency.

A simple rule of thumb will be to place the wifi router at the test location and check using a laptop installed with Netstumber if the usual computing location can have a good received signal from the wifi router. (i.e. To have a received signal level as far away from the detected ambient noise is possible )

For example, if the ambient noise is -99dB, it is better to have a received signal level of -60dB than -80dB. Having a strong received signal level as far away from noise means that it will not be affected by noise and hence will be a strong and reliable signal.

If you need additional help, do not hesitate to contact me for more info.